F5 vs is intermittently not responding to ICMP

We are using Cisco GSS to monitor F5 vs using ICMP. For unknown reason vs is intermittently not responding to the ping but accept production traffic, in our case is HTTP. If ICMP failed then GSS will not give A record (vs IP) to the requester. We are running BIG-IP 11.5.2 Build 0.0.141 Final.